diff --git a/node/node-0.10.d.ts b/node/node-0.10.d.ts
index 5c095596c4..2f3824462d 100644
--- a/node/node-0.10.d.ts
+++ b/node/node-0.10.d.ts
@@ -910,6 +910,7 @@ declare module "fs" {
     }
     export interface WriteStream extends stream.Writable {
         close(): void;
+        bytesWritten: number;
     }
 
     export function rename(oldPath: string, newPath: string, callback?: (err?: NodeJS.ErrnoException) => void): void;
diff --git a/node/node.d.ts b/node/node.d.ts
index 6544d3c10c..7aaa176edc 100644
--- a/node/node.d.ts
+++ b/node/node.d.ts
@@ -1056,6 +1056,7 @@ declare module "fs" {
     }
     export interface WriteStream extends stream.Writable {
         close(): void;
+        bytesWritten: number;
     }
 
     /**